Factors Influencing Flowability of Microbial Gel Filling Materials and Optimization of Ratios Using Design of Experiments Method

Abstract

Abstract During coal mining, a significant amount of coal gangue is generated. The coal gangue occupies a considerable amount of land resources and causes environmental damage to the surrounding areas. Currently, the utilization rate of coal gangue is low. To address this issue, this study employed a method that combines a water-absorbent resin with microbially induced calcium carbonate precipitation (MICP) to prepare paste-filling materials. The water retention properties of the water-absorbent resin provide continuous reaction sites for MICP, increasing the calcium carbonate nucleation points and thereby solidifying the coal gangue into paste materials. A design of experiments (DOE) mixture scheme was utilized to conduct tests on the water seepage, slump, and expansion of the paste material, analyze the influence of material composition on its flowability, and optimize the ratios. Through electron microscopy, the morphology and distribution of calcium carbonate crystals during the solidification process were examined. Accordingly, the mechanism by which the water-absorbent resin combined with MICP solidified coal gangue in preparation of paste-filling materials was revealed. The findings of this research provide a theoretical foundation and technical support for engineering applications.